HVAC systems for buildings are a major consumer of electrical energy. Controlling such systems efficiently and effectively in the presence of dynamic interaction and random disturbance so as to conserve energy while maintaining the desired thermal comfort level requires more than a conventional methodology. With increasing complexity of modem HVAC systems such as multi split systems (Variable Refrigerant Volume systems with multiple evaporators), controlling and optimizing the operation with guaranteed performance, stability and reliability becomes a challenging issue. In addition, complex HVAC systems have a variety of system configurations to meet customers' needs, different operating conditions, and varying environmental conditions. Innovative control design is needed to provide desired system performance and reliability and to dramatically reduce the time and cost of control design processes for complex HVAC systems.